The present invention relates generally to accumulating conveyors and more particularly to a control system for a zero pressure accumulating conveyor wherein loads accumulate without contacting one another.
In automated conveyor systems, it is common to accumulate the articles being conveyed at the downstream end of the conveyor system. For example, during a disruption in a downstream process, articles on the conveyor are sometimes allowed to accumulate or backup on the conveyor. Also, articles are sometimes allowed to accumulate so that some other process, such as packaging, can be performed on the articles before being sent downstream.
In general, an accumulating conveyor has a plurality of zones extending from an inlet end of the conveyor to the discharge end. In existing state of the art accumulating conveyors, all zones are normally live. The zones are deactivated only when there is an obstruction, such as another load, in the immediately adjacent downstream zone. When an article is stopped at a discharge end of the conveyor, the zones are successively deactivated from the discharge end back toward the inlet end as the loads accumulate. When the load at the discharge end is removed, the zones are reactivated in sequence from the discharge end to the inlet end.
One drawback with existing state of the art accumulating conveyors is that many zones will continue to be operated even when they are empty resulting in an unnecessary waste of energy and an easily avoidable wear on mechanical components. At any given moment, up to 90% of the conveyor may be empty. Nevertheless, the main drive system, including typically a motor, gear box, chains or belts, rollers, idlers and other mechanical devices, are in motion consuming energy and creating noise, dust, and unnecessary wear on mechanical components. As a result, existing accumulating conveyors are inefficient and costly to operate.